1. Field of the Invention
The invention relates generally to holders for storing and retaining ligating devices such as surgical staples and hemostatic clips prior to use. More particularly, the invention relates to cartridges which facilitate the storage and retention of a plurality of ligating devices within a corresponding plurality of individual chambers of the cartridge prior to withdrawal of the devices by a forceps-type applier.
2. Description of the Prior Art
Hemostatic or ligating clips have long been used to ligate or clamp blood vessels during surgical procedures. The terms "hemostatic" and "ligating" are interchangeably used herein to mean any clips which squeeze tissue to effect a blockage. While the clips are usually integrally formed, in some applications such as aneurysm clips the devices are formed of more than one piece. The clips are generally made of either a biocompatible metallic material or of a polymeric or non-metallic material. While it is convenient to describe the invention in terms of hemostatic clips, to the extent that staples and clips are similar medical devices it will be understood that the present invention is adaptable for use with ligating devices such as surgical staples. For ease of explanation, the term "clips" will be used herein but this should be understood to encompass "staples" as well.
In general, the clips are C-shaped, U-shaped or V-shaped when in their open configuration and are designed such that the opposing legs of the open clip are able to be closed together by being compressed by the jaws of a forceps-type clip applier. In the case of surgical staples the staple profile may be a slight variation of an open "C", "V" or "U". For example, one type of staple adaptable for use with the present invention is shown in U.S. Pat. No. 4,375,866 (Giersch et al.), assigned to the assignee hereof and incorporated by reference herein. In the case of metallic clips, the material is sufficiently strong such that the clips remain in their crimped, closed position merely by squeezing the legs together. In the case of plastic-type clips, the material is not as strong and requires some auxiliary latching mechanism to keep the clips closed. For the foregoing reasons, metallic clips are generally symmetrical while plastic clips are not. The latching mechanism of the latter generally comprises a hook-type arrangement molded with or otherwise secured to the plastic clip. One example of such a plastic ligating clip is shown in U.S. Pat. No. 4,834,096 (Oh et al.) assigned to the assignee hereof.
Because hemostatic clips are small and because many clips are usually used in a surgical procedure, holding devices or cartridges are used to store and retain the clips--whether metallic or plastic--between the time of their manufacture and their ultimate use in a surgical procedure. While numerous clip cartridges are known, they all serve to prevent the clips from becoming loosened during shipment and handling and from becoming completely dislodged. A distinction should be made between clip cartridges intended for use with "manual" clip appliers and those intended for use with "automatic" clip appliers. As used herein, the term "automatic" means those clip appliers which retain a plurality of hemostatic clips adjacent the jaws of a clip applier in a way such that a new clip is automatically fed to the jaws after the previous clip has been crimped into place. As used herein, the term "manual" means clip appliers which receive one clip at a time between the jaws and which have to be reloaded manually after the previous clip is crimped. The reloading operation is generally accomplished by inserting the jaws of the applier into a clip holder or cartridge which is generally provided with a plurality of longitudinally spaced, clip retaining chambers. A single clip is retained in each chamber by a variety of means, legs facing downwardly, and is removed from its chamber by a forceps-type clip applier which is inserted into each clip chamber and secured to the clip sufficiently to overcome whatever clip retention means is utilized to enable the clip to be removed from the clip chamber. The jaws of the clip applier generally have longitudinal grooves to receive the clip legs and may have end-dams at the distal end of each groove to limit distal movement of the clip. The clip is secured in the jaws by the natural resiliency of the clip legs and by the end-dams if they are present.
Various mechanisms are known by which clips may be retained within the chambers of clip cartridges for use with manual clip appliers. In all instances, a desirable goal of such cartridges is to minimize the forces required to load the clip into the applier and to then remove it from the cartridge while maximizing the security with which the clip is held in the cartridge and, subsequently, the applier jaws prior to use. With respect to metallic clips in manual clip cartridges, friction between the clip and other surfaces within its individual chamber is generally sufficient to retain the clip. Cartridges may be categorized according to the surfaces by which the frictional forces are applied to the clip: side wall, end wall or central post.
The clip cartridges are generally made of molded plastic material (for example, polycarbonate or polyphenoline oxide) such that the walls of each clip chamber are somewhat resilient. Consequently, with respect to side wall type cartridges designed to hold clips by frictional engagement with the side walls, the latter are sometimes able to be pushed away from each other (longitudinally) when the clip applier jaws are inserted into the chamber to retrieve the clip. Examples of cartridges holding the clips in their respective clip chambers by means of frictional engagement with the side walls of each chamber is shown in U.S. Pat. No. 4,076,120 (Carroll et al.) and U.S. Pat. No. 4,961,499 (Kulp). Another type of known prior art side wall cartridge has a plurality of ribs extending longitudinally from each side wall of each clip chamber inwardly toward the clip to retain the clip by frictional engagement with the ribs (U.S. Pat. No. 4,696,396, Samuels). However, such configurations result in frictional contact between the side walls and the applier, thus resulting in some force being required to remove the loaded applier. Prior to the subject invention, all side wall type cartridges required some force to be applied to the applier to remove it and the clip from the cartridge.
In some prior art clip cartridges, each individual clip chamber is provided with a central post generally conforming to the shape of the open clip although being slightly larger so that when the clip is pushed onto the central post the legs are spread slightly so that frictional contact between the legs of the clip and the central post retains the clip within its chamber. Cartridges of this "central post" type are shown in U.S. Pat. Nos. 3,270,745, 3,326,216, 3,363,628, 3,439,522 and 3,439,523, all issued to E. C. Wood. While such cartridges serve to securely retain clips, the friction required to retain the clips in the cartridges also makes it more difficult to load the clips into the jaws of a clip applier and to then remove the clip from the cartridge. As the jaws are pushed down onto the clip the central post keeps the clip legs from closing, thereby forcing the jaws away from each other. If the jaws merely have a groove to receive the clip legs, the frictional force between the jaws and the clip must be greater than that between the clip legs and the post in order for the clip to be removed. If the jaws have an end-dam at the distal tip of each groove, the clip may be more easily removed from central-post type cartridges (and others) because the end-dams act directly on the clip legs with whatever upward removal force is applied to the applier. However, in situations where the clip is roughened or coated to enhance its tissue gripping ability, the frictional contact between the clip legs and the post is even greater than normal and, consequently, an even greater removal force is required. An example of such clips is disclosed in copending U.S. patent application Ser. No. 07/790,104 assigned to the assignee hereof and incorporated by reference herein. Even if the clips are not coated or roughened, the frictional contact between the post and the clip may be sufficient to leave a residue of particulate matter caused by the clip shaving the post. Minimizing the amount of this particulate is an object of this invention.
In order to minimize the forces associated with clip removal some prior art cartridges retain unformed clips (i.e. clips in a partially straightened state) by maintaining each clip under tension within its chamber by the interaction between the central post in the chamber, the central (hinge) part of the clip and protrusions extending transversely into each chamber toward the central post. These are termed end-wall type cartridges. Each clip is retained in its chamber by having its central hinge part pushed upwardly by the central post and its ends pushed downwardly by the protrusions. Such a cartridge is shown in U.S. Pat. No. 3,713,533 (Reimels) and U.S. Pat. No. 4,146,130 (Samuels et al.)
The aforementioned U.S. Pat. No. 4,146,130 (Samuels et al.) shows an alternative embodiment for the situation where clips ar intended to be loosely maintained in the cartridge without frictional engagement between it and the chamber, the clips in such an event being retained in each cartridge by a covering tape which may be easily severed by the applier as desired. However, it is generally not desirable to have metallic clips too loosely held within clip cartridges since the orientation of the clips is then subject to change. If the clips are not consistently held in a certain orientation, it is difficult to load the clips into clip appliers because the clip legs are not consistently aligned with the grooves of the applier jaws. Consequently, a force-balancing process has to be considered to produce a cartridge having sufficient clip holding or storage force and minimal (or zero) clip removing force.
Another end-wall type prior art clip cartridge is shown in U.S. Pat. Nos. 4,936,447 (Peiffer) and 4,972,949 (Peiffer) which shows a formed metallic clip being held within a clip compartment by being supported on a central post by a pair of inwardly extending transverse resilient fingers. The fingers are pushed downwardly by the distal tips of clip appliers so that as the clip legs are received in the grooves in the jaws in the clip applier the resilient fingers are pushed out of the way. With this device, since the grooves in the applier jaws do not have any end-dams, the clip must be slightly compressed as it is loaded into the jaws of the applier in order to produce enough frictional contact between the clip and jaws to prevent the clip from falling out. The Peiffer cartridge, however, is not suitable for use with clip appliers having end-dams since the end-dams would necessarily cause the clip legs to be compressed inwardly too much because there is nothing to support the legs to prevent closure. Therefore, when the dams clear the end of the clip leg the clip, having been compressed to a point where it does not have sufficient resiliency to firmly occupy the space between the grooves in the jaws, would not be securely retained within the jaws. While this device does offer low, desirable clip removal forces, the absence of end-dams in the jaws of the applier mandated by this device results in compromised clip security in the jaws.
It is an object of this invention to produce a clip cartridge for supporting metallic clips in a manner which minimizes the force with which the clip may be loaded into a forceps-type clip applier, minimizes the force with which the clip may be removed from the cartridge and is suitable for use with a clip applier having end-dams in the clip jaws or not having such end-dams.
It is an object of this invention to produce a hemostatic clip cartridge which minimizes the forces associated with the loading of clips into a forceps-type clip applier.
It is another object of this invention to provide a hemostatic clip cartridge for retaining clips during shipping and handling while enabling the withdrawal of the clips by clip appliers in preparation for use.
It is a further object of this invention to produce a hemostatic clip cartridge for storing and retaining a plurality of metallic hemostatic clips, prior to their subsequent removal by an associated clip applier, in a manner which minimizes the inward displacement of the clip legs during the loading of the clip into a forceps-type clip applier.
It is also an object of this invention to produce a clip cartridge for storing and retaining a plurality of hemostatic clips and for minimizing forces associated with the subsequent removal of a clip by an associated clip applier.
It is an additional object of this invention to produce a hemostatic clip cartridge of the side wall type in which frictional forces between the clip applier and the side walls are substantially reduced (if not eliminated) after the clip has been engaged in the applier jaws.
It is also an object of this invention to produce a clip cartridge for storing and retaining a plurality of hemostatic clips and for minimizing forces associated with the subsequent removal of a clip by an associated clip applier to such an extent that the loaded applier may be lifted from the cartridge without holding the cartridge down.
It is another object of this invention to produce a hemostatic clip cartridge suitable for storing and retaining a plurality of hemostatic clips which have been coated with a grip enhancing material and for minimizing forces associated with the subsequent removal of a clip by an associated clip applier.
It is yet another object of this invention to produce a cartridge for storing and retaining a plurality of generally C-shaped ligating devices (such as clips and staples) and for minimizing the forces required to remove the ligating devices by associated appliers.